Project modernization (#630)

* Fixed boats falling and a TP glitch #266

* Replaced every C-style cast with C++ ones

* Replaced every C-style cast with C++ ones

* Fixed boats falling and a TP glitch #266

* Updated NULL to nullptr and fixing some type issues

* Modernized and fixed a few bugs

- Replaced most instances of `NULL` with `nullptr`.
- Replaced most `shared_ptr(new ...)` with `make_shared`.
- Removed the `nullptr` macro as it was interfering with the actual nullptr keyword in some instances.

* Fixing more conflicts

* Replace int loops with size_t and start work on overrides

Minecraft.World/HouseFeature.cpp

@@ -185,7 +185,7 @@ bool HouseFeature::place(Level *level, Random *random, int x, int y, int z)
 		}
 	}
 
-	shared_ptr<PigZombie>(pz) = shared_ptr<PigZombie>(new PigZombie(level));
+	shared_ptr<PigZombie>(pz) = std::make_shared<PigZombie>(level);
 	pz->moveTo(x0 + w / 2.0 + 0.5, y0 + 0.5, z0 + d / 2.0 + 0.5, 0, 0);
 	level->addEntity(pz);